staging: comedi: comedi_internal.h inclusion guards

Add a multiple inclusion guard macro to "comedi_internal.h".
Signed-off-by: Ian Abbott <abbotti@mev.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/comedi/comedi_internal.h

+#ifndef _COMEDI_INTERNAL_H
+#define _COMEDI_INTERNAL_H
+
 /*
  * various internal comedi stuff
  */
@@ -14,3 +17,5 @@ int comedi_buf_alloc(struct comedi_device *dev, struct comedi_subdevice *s,
 
 extern unsigned int comedi_default_buf_size_kb;
 extern unsigned int comedi_default_buf_maxsize_kb;
+
+#endif /* _COMEDI_INTERNAL_H */